There's a couple subreddits that have good posts on powerbanks; both /r/Flashlight and /r/18650MasterRace discuss this all the time. To save you some trouble, here's a good comparison for powerbanks that accept a micro USB input.

There's a couple subreddits that have good posts on powerbanks; both /r/Flashlight and /r/18650MasterRace discuss this all the time. To save you some trouble, here's a good comparison for powerbanks that accept a micro USB input.